MAXIM MAX630, MAX4193 User Manual

General Description

Maxim’s MAX630 and MAX4193 CMOS DC-DC regula­tors are designed for simple, efficient, minimum-size
DC-DC converter circuits in the 5mW to 5W range. The
MAX630 and MAX4193 provide all control and power
handling functions in a compact 8-pin package: a

1.31V bandgap reference, an oscillator, a voltage com­parator, and a 375mA N-channel output MOSFET. A
comparator is also provided for low-battery detection.

Operating current is only 70µA and is nearly indepen­dent of output switch current or duty cycle. A logic-level
input shuts down the regulator to less than 1µA quies­cent current. Low-current operation ensures high effi­ciency even in low-power battery-operated systems.
The MAX630 and MAX4193 are compatible with most
battery voltages, operating from 2.0V to 16.5V.

The devices are pin compatible with the Raytheon bipo­lar circuits, RC4191/2/3, while providing significantly
improved efficiency and low-voltage operation. Maxim
also manufactures the MAX631, MAX632, and MAX633
DC-DC converters, which reduce the external compo­nent count in fixed-output 5V, 12V, and 15V circuits.
See Table 2 at the end of this data sheet for a summary
of other Maxim DC-DC converters.

Applications

+5V to +15V DC-DC Converters
High-Efficiency Battery-Powered DC-DC

Converters
+3V to +5V DC-DC Converters
9V Battery Life Extension
Uninterruptible 5V Power Supplies
5mW to 5W Switch-Mode Power Supplies

Features

♦ High Efficiency—85% (typ)
♦ 70µA Typical Operating Current
♦ 1µA Maximum Quiescent Current
♦ 2.0V to 16.5V Operation
♦ 525mA (Peak) Onboard Drive Capability
♦ ±1.5% Output Voltage Accuracy (MAX630)
♦ Low-Battery Detector
♦ Compact 8-Pin Mini-DIP and SO Packages
♦ Pin Compatible with RC4191/2/3

MAX630/MAX4193

CMOS Micropower Step-Up

Switching Regulator

________________________________________________________________ Maxim Integrated Products 1

I

C

+V

S

GND

1

2

87LBD

V

FB

C

X

L

X

LBR

TOP VIEW

3

4

6

5

MAX630

MAX4193

Pin Configuration

Ordering Information

MAX630

+5V IN

470μH

+15V
OUT

47pF

8

LBD

1

LBR

2

C

X

4

GND

7

V

FB

3

L

X

6

I

C

5

+V

S

+5 TO +15V CONVERTER

Typical Operating Circuit

19-0915; Rev 2; 9/08

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

*Dice are specified at TA= +25°C. Contact factory for dice
specifications.

**Contact factory for availability and processing to MIL-STD-883.
†Contact factory for availibility.

PART TEMP RANGE

MAX630CPA 0°C to +70°C 8 PDIP

MAX630CSA 0°C to +70°C 8 SO
MAX630CJA 0°C to +70°C 8 CERDIP
MAX630EPA -40°C to +85°C 8 PDIP
MAX630ESA -40°C to +85°C 8 SO
MAX630EJA -40°C to +85°C 8 CERDIP
MAX630MJA -55°C to +125°C 8 CERDIP**
MAX630MSA/PR -55°C to +125°C 8 SO†
M AX 630M S A/P R- T -55°C to +125°C 8 SO†
MAX4193C/D 0°C to +70°C Dice*
MAX4193CPA 0°C to +70°C 8 PDIP
MAX4193CSA 0°C to +70°C 8 SO
MAX4193CJA 0°C to +70°C 8 CERDIP
MAX4193EPA -40°C to +85°C 8 PDIP
MAX4193ESA -40°C to +85°C 8 SO
MAX4193EJA -40°C to +85°C 8 CERDIP
MAX4193MJA -55°C to +125°C 8 CERDIP**

PIN­PACKAGE

MAX630/MAX4193

CMOS Micropower Step-Up
Switching Regulator

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(+VS= +6.0V, TA= +25°C, IC= 5.0µA, unless otherwise noted.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

Supply Voltage .......................................................................18V

Storage Temperature Range ............................-65°C to +160°C

Lead Temperature (soldering, 10s) .................................+300°C

Operating Temperature Range

MAX630C, MAX4193C........................................0°C to +70°C

MAX630E, MAX4193E .....................................-40°C to +85°C

MAX630M, MAX4193M..................................-55°C to +125°C

Power Dissipation

8-Pin PDIP (derate 6.25mW/°C above +50°C).............468mW

8-Pin SO (derate 5.88mW/°C above +50°C)................441mW

8-Pin CERDIP (derate 8.33mW/°C above +50°C)........833mW

Input Voltage (Pins 1, 2, 6, 7) .....................-0.3V to (+V

S

+ 0.3V)

Output Voltage, L

X

and LBD ..................................................18V

L

X

Output Current ..................................................525mA (Peak)

LBD Output Current ............................................................50mA

MAX630 MAX4193

PARAMETER

CONDITIONS

UNITS

Operating 2.0

Supply Voltage +V

S

Startup 1.9

2.4

V

Internal Reference Voltage V

REF

V

Switch Current I

SW

V3 = 400mV 75

75

mA

Supply Current (at Pin 5) I

S

I3 = 0mA 70

90 µA

Efficiency 85 85 %

Line Regulation

0.5V

0

< VS < V

0

(Note 1)

0.2

0.5

% V

OUT

Load Regulation

V

S

= +5V, P

LOAD

= 0 to

150mW (Note 1)

0.5 0.2 0.5

% V

OUT

Operating Frequency Range

F

O

(Note 2) 0.1 40 75 0.1 25 75 kHz

Reference Set Internal
Pulldown Resistance

R

IC

V6 = V

S

0.5

10 0.5 1.5 10 MΩ

Reference Set Input Voltage
Threshold

V

IC

0.2

1.3 0.2 0.8 1.3 V

Switch Current I

SW

V3 = 1.0V

mA

Switch Leakage Current I

CO

V3 = 16.5V

1.0

5.0 µA

Supply Current (Shutdown) I

SO

IC < 0.01µA

1.0

5.0 µA

Low-Battery Bias Current I

LBR

10

10 nA

Capacitor Charging Current I

CX

30 30 µA

CX+ Threshold Voltage +VS - 0.1 +VS - 0.1 V

CX- Threshold Voltage

0.1 V

VFB Input Bias Current I

FB

10

10 nA

Low-Battery Detector Output
Current

I

LBD

V8 = 0.4V, V1 = 1.1V

µA

Low-Battery Detector Output
Leakage

I

LBDO

V8 = 16.5V, V1 = 1.4V

5.0

5.0 µA

SYMBOL

MIN TYP MAX MIN TYP MAX

1.29 1.31 1.33 1.24 1.31 1.38

150

16.5

150

125

16.5

100 100

250 600 250 600

0.08

0.2

1.5

0.8

0.01

0.01

0.01

0.1

0.01

0.01

0.06

0.01

0.01

0.01

0.01

0.01

MAX630/MAX4193

CMOS Micropower Step-Up

Switching Regulator

_______________________________________________________________________________________ 3

LX ON-RESISTANCE vs.

TEMPERATURE

MAX630/4193 toc01

TEMPERATURE (°C)

L

X

R

ON

(Ω)

1007550250-25-50

2

4

6

8

0

125

+VS = 2.5V

+VS = 6V

+VS = 16V

SUPPLY CURRENT vs.

TEMPERATURE

MAX630/4193 toc02

TEMPERATURE (°C)

I

S

(μA)

1007550250-25-50

40

20

80

60

120

100

140

0

125

SUPPLY CURRENT vs.

SUPPLY VOLTAGE

MAX630/4193 toc03

+VS (V)

I

S

(μA)

1412108642

50

150

100

250

200

300

16

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

ELECTRICAL CHARACTERISTICS

(+VS= +6.0V, TA= Full Operating Temperature Range, IC= 5.0µA, unless otherwise noted.)

MAX630 MAX4193

PARAMETER

CONDITIONS

UNITS

Supply Voltage +V

S

V

Internal Reference Voltage V

REF

V

Supply Current (Pin 5) I

S

I3 = 0mA 70

90

µA

Line Regulation

0.5V

0UT

< VS < V

0UT

(Note 1)

0.5

1.0

% V

OUT

Load Regulation

V

S

= 0.5V0, PL = 0 to

150mW (Note 1)

1.0

1.0

% V

OUT

0°C ≤ TA ≤
+70°C

10

10

-40°C ≤ TA ≤
+85°C

10

10

Reference Set Internal
Pulldown Resistance

R

IC

-55°C ≤ TA ≤
+125°C

10

10

MΩ

Reference Set Input Voltage
Threshold

V

IC

1.3

1.3 V

Switch Leakage Current I

CO

V3 = 16.5V

30

30 µA

Supply Current (Shutdown) I

SO

IC < 0.01µA

10

30 µA

Low-Battery Detector Output
Current

I

LBD

V8 = 0.4V, V1 = 1.1V

µA

Note 1: Guaranteed by correlation with DC pulse measurements.
Note 2: The operating frequency range is guaranteed by design and verified with sample testing.

SYMBOL

V6 = V

S

MIN TYP MAX MIN TYP MAX

2.2 16.5 3.5 16.5

1.25 1.31 1.37 1.20 1.31 1.42

0.2

0.5

0.45 1.5

0.4 1.5

0.3 1.5

0.2 0.8

0.1

0.01

250 600 250 600

200

300

0.5

0.5

0.45 1.5

0.4 1.5

0.3 1.5

0.2 0.8

0.1

0.01

Detailed Description

The operation of the MAX630 can best be understood
by examining the voltage regulating loop of Figure 1.
R1 and R2 divide the output voltage, which is com­pared with the 1.3V internal reference by comparator
COMP1. When the output voltage is lower than desired,
the comparator output goes high and the oscillator out­put pulses are passed through the NOR gate latch,
turning on the output N-channel MOSFET at pin 3, LX.
As long as the output voltage is less than the desired
voltage, pin 3 drives the inductor with a series of pulses
at the oscillator frequency.

Each time the output N-channel MOSFET is turned on,
the current through the external coil, L1, increases,
storing energy in the coil. Each time the output turns off,
the voltage across the coil reverses sign and the volt­age at LXrises until the catch diode, D1, is forward
biased, delivering power to the output.

When the output voltage reaches the desired level,

1.31V x (1 + R1 / R2), the comparator output goes low
and the inductor is no longer pulsed. Current is then
supplied by the filter capacitor, C1, until the output volt­age drops below the threshold, and once again LXis
switched on, repeating the cycle. The average duty
cycle at LXis directly proportional to the output current.

Output Driver (LX Pin)

The MAX630/MAX4193 output device is a large
N-channel MOSFET with an on-resistance of 4Ω and a
peak current rating of 525mA. One well-known advan­tage that MOSFETs have over bipolar transistors in
switching applications is higher speed, which reduces
switching losses and allows the use of smaller, lighter,
less costly magnetic components. Also important is that
MOSFETs, unlike bipolar transistors, do not require
base current that, in low-power DC-DC converters,
often accounts for a major portion of input power.

The operating current of the MAX630 and MAX4193
increases by approximately 1µA/kHz at maximum
power output due to the charging current required by
the gate capacitance of the LXoutput driver (e.g., 40µA
increase at a 40kHz operating frequency). In compari­son, equivalent bipolar circuits typically drive their NPN
LXoutput device with 2mA of base drive, causing the
bipolar circuit’s operating current to increase by a fac­tor of 10 between no load and full load.

Oscillator

The oscillator frequency is set by a single external, low­cost ceramic capacitor connected to pin 2, CX. 47pF
sets the oscillator to 40kHz, a reasonable compromise
between lower switching losses at low frequencies and
reduced inductor size at higher frequencies.

MAX630/MAX4193

CMOS Micropower Step-Up
Switching Regulator

4 _______________________________________________________________________________________

Pin Description

PIN NAME FUNCTION

1 LBR

Low-Battery Detection Comparator Input. The LBD output, pin 8, sinks current whenever this pin is
below the low-battery detector threshold, typically 1.31V.

2C

X

An external capacitor connected between this terminal and ground sets the oscillator frequency.
47pF = 40 kHz.

3L

X

This pin drives the external inductor. The internal N-channel MOSFET that drives LX has an output
resistance of 4Ω and a peak current rating of 525mA.

4 GND Ground

5+VSThe positive supply voltage, from 2.0V to 16.5V (MAX630).

6I

C

The MAX630/MAX4193 shut down when this pin is left floating or is driven below 0.2V. For normal
operation, connect I

C

directly to +VS or drive it high with either a CMOS gate or pullup resistor

connected to +V

S

. The supply current is typically 10nA in the shutdown mode

7V

FB

The output voltage is set by an external resistive divider connected from the converter output to V

FB

and ground. The MAX630/MAX4193 pulse the LX output whenever the voltage at this terminal is less
than 1.31V.

8 LBD

The Low-Battery Detector output is an open-drain N-channel MOSFET that sinks up to 600μA (typ)
whenever the LBR input, pin 1, is below 1.31V.

Low-Battery Detector

The low-battery detector compares the voltage on LBR
with the internal 1.31V reference. The output, LBD, is an
open-drain N-channel MOSFET. In addition to detecting
and warning of a low battery voltage, the comparator
can also perform other voltage-monitoring operations
such as power-failure detection.

Another use of the low-battery detector is to lower the
oscillator frequency when the input voltage goes below
a specified level. Lowering the oscillator frequency
increases the available output power, compensating for
the decrease in available power caused by reduced
input voltage (see Figure 5).

Logic-Level Shutdown Input

The shutdown mode is entered whenever IC(pin 6) is
driven below 0.2V or left floating. When shut down, the

MAX630’s analog circuitry, oscillator, LX, and LBD out­puts are turned off. The device’s quiescent current dur­ing shutdown is typically 10nA (1µA max).

Bootstrapped Operation

In most circuits, the preferred source of +VSvoltage for
the MAX630 and MAX4193 is the boosted output volt­age. This is often referred to as a “bootstrapped” oper­ation since the circuit figuratively “lifts” itself up.

The on-resistance of the N-channel LX output decreas­es with an increase in +VS; however, the device operat­ing current goes up with +VS(see the Typical
Operating Characteristics, ISvs. +VSgraph). In circuits
with very low output current and input voltages greater
than 3V, it may be more efficient to connect +VSdirect­ly to the input voltage rather than bootstrap.

MAX630/MAX4193

CMOS Micropower Step-Up

Switching Regulator

_______________________________________________________________________________________ 5

COMP 2

+5V INPUT

R3

169kΩ

R4
100kΩ

L1
470

LOW BATTERY INPUT

1.31V

OSC

RON ≅ 3Ω

40kHz

COMP 1

1.31V

BANDGAP

REFERENCE

AND

BIAS GENERATOR

1 LBR

2C

X

3L

X

4 GND

D1
1N4148

+VS5

I

C

6

V

FB

7

LBD 8

LOW-BATTERY OUTPUT
(LOW IF INPUT < 3V)

C

C

R1
499kΩ

R2

47.5kΩ

SHUTDOWN

OPERATE

+15V OUTPUT
20mA

C1
470μF
25V

MAX630

COMP 2

Figure 1. +5V to +15V Converter and Block Diagram